Pseudo first-order rate constants for the cleavage of the six isomeric trimethylsilylxylenes by fi-toluenesulfonic acid in acetic acid have been determined at 25'. Although the cleavage reactions parallel usual electrophilic substitutions, they are considerably influenced by buttressing and steric strain effects. The order of increase in the rate of acid cleavage for the trimethylsilylxylenes is (R= trimethylsilyl): 5-Rm-xylene< 4-Ro-xylene< 2-Rp-xylene< 3-Ro ...
